1. Field of the Invention
This invention pertains to the preparation of (poly)cyclic polyethers. Cyclic polyethers comprised of certain oxyalkylene units are known to selectively complex certain alkali and alkaline earth metal cations as well as other cationic species; C. J. Pedersen, U.S. Pat. Nos. 3,562,295 and 3,686,225.
2. Description of the Prior Art
Preparation of the cyclic tetramer of ethylene oxide by the cyclization of ethylene oxide over an organo-metallic catalyst, for example triethyl aluminum, ethyl zinc butoxide or diethyl magnesium, is taught by Stewart, et al. in British patent Specification No. 785,229. C. J. Pedersen in U.S. Pat. No. 3,687,978 teaches the preparation of macrocyclic polyethers by the reaction of vicinal aromatic diols with .alpha.,.omega.-dihalides of polyoxyalkylene materials and sodium hydroxide in 1-butanol solvent. Pedersen also describes the preparation of the cyclic oxyethylene hexamer by the autoelimination reaction of the .alpha.,.omega.-chlorohydrin of hexaethylene glycol in the presence of potassium t-butoxide in a 1,2-dimethoxy ethylene solvent in U.S. Pat. No. 3,562,295. The ethylene oxide cyclic hexamer is produced in a very low yield of 1.8%. Dale et al. describe a base catalyzed preparation in Chem. Comm. 670 (1971). There, glycols and glycol ditosylates are condensed with potassium t-butoxide in benzene in about 15-35% yields.